Cortical neural computation by discrete results hypothesis

One of the most challenging problems we face in neuroscience is to understand how the cortex performs computations. There is increasing evidence that the power of the cortical processing is produced by populations of neurons forming dynamic neuronal ensembles. Theoretical proposals and multineuronal experimental studies have revealed that ensembles of neurons can form emergent functional units. However, how these ensembles are implicated in cortical computations is still a mystery. Although cell ensembles have been associated with brain rhythms, the functional interaction remains largely unclear. It is still unknown how spatially distributed neuronal activity can be temporally integrated to contribute to cortical computations. A theoretical explanation integrating spatial and temporal aspects of cortical processing is still lacking. In this Hypothesis and Theory article, we propose a new functional theoretical framework to explain the computational roles of these ensembles in cortical processing. We suggest that complex neural computations underlying cortical processing could be temporally discrete and that sensory information would need to be quantized to be computed by the cerebral cortex. Accordingly, we propose that cortical processing is produced by the computation of discrete spatio-temporal functional units that we have called “Discrete Results” (Discrete Results Hypothesis). This hypothesis represents a novel functional mechanism by which information processing is computed in the cortex. Furthermore, we propose that precise dynamic sequences of “Discrete Results” is the mechanism used by the cortex to extract, code, memorize and transmit neural information. The novel “Discrete Results” concept has the ability to match the spatial and temporal aspects of cortical processing. We discuss the possible neural underpinnings of these functional computational units and describe the empirical evidence supporting our hypothesis. We propose that fast-spiking (FS) interneuron may be a key element in our hypothesis providing the basis for this computation.Work was supported by a grant from Ministerio de Economía y Competitividad (BFU2012-36107

El núcleo posterior medial del tálamo y su implicación en los procesos perceptivos y cognitivos

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Anatomía, Histología y Neurociencia. Fecha de lectura: 11-05-2021Se desconoce en gran medida cómo el sistema somestésico extrae información del flujo de señales sensoriales. La información procedente de las vibrisas es procesada principalmente por dos vías ascendentes paralelas hacia la corteza cerebral. Sin embargo, se desconoce la implicación funcional de las diferentes estructuras que componen dichas rutas. Mediante la combinación de técnicas electrofisiológicas y farmacológicas in vivo en ratas, encontramos diferencias significativas entre estas vías. Aunque está bien asumido que el POm y el VPM responden a la estimulación de las vibrisas contralaterales, encontramos que el primero es capaz de responder también a las ipsilaterales. Mediante la integración de señales simultaneas procedentes de vibrisas en ambos lados de la cara, está implicado en la representación de eventos táctiles bilaterales. Esto demuestra la implicación de los núcleos talámicos sensoriales de tipo 'higher-order' en la percepción bilateral. Encontramos que los núcleos POm están mutuamente conectados a través de la corteza formando un bucle o 'loop' funcional. Revelamos la naturaleza y el contenido de los mensajes transmitidos a través de este circuito mostrando que dichos mensajes son 'patrones estructurados de actividad sostenida'. Estos mensajes son transmitidos preservando su estructura integrada. La implicación de diferentes áreas fue investigada descubriendo que S1 juega un papel protagonista en dicho 'loop' POm-POm. También encontramos diferente implicación laminar en esta área en el procesamiento de actividad sostenida y en su transmisión entre hemisferios. Proponemos un modelo teórico en el que dichos 'patrones estructurados de actividad sostenida' generados por el POm pueden jugar un papel relevante en las funciones perceptivas, motoras y cognitivas. Además, demostramos que el POm está involucrado en la representación de patrones sensoriales complejos. Este núcleo es muy sensible a la activación simultanea de las vibrisas y a las complejas interacciones espaciotemporales que se producen entre ellas. La estructura espaciotemporal de dichos patrones y la complejidad de sus partes son reflejados en precisos cambios de actividad en el POm. Nuestros resultados sugieren que este núcleo podría ser un codificador general de patrones. La naturaleza (estructurada versus discreta), el tipo (sostenido versus transitorio) y el contenido (integrado versus segregado) de la actividad neural procesada y transmitida por estos núcleos determina su implicación funcional y puede permitir clasificarlos. Proponemos la hipótesis de los Componentes Complementarios para explicar estas diferencias. Además, revelamos la capacidad del POm para ajustar el procesamiento en las cortezas S1 y S2 mediante la inducción de una precisa inhibición en determinadas capas corticales. Esta modulación está mediada por neuronas GABAérgicas de la capa 1. La hipótesis de Computación Cortical por Resultados Discretos propuesta aquí puede explicar la implicación funcional de dicho ajust

“Rev Int Med Cienc Ac”. A bibliometric approach to the 2000-2011 period

La Revista Internacional de Ciencias de la Actividad Física y del Deporte es una revista española indexada en las dos bases de datos más importantes a nivel internacional sobre las que se calculan los índices de impacto: Web of Science y Scopus. El presente trabajo analiza bibliométricamente esta revista desde su nacimiento hasta el año 2011. En total se publicaron 287 artículos, con un promedio de 2,8 autorías por trabajo. Se concluye que es una de las mejores revistas en lengua española de ciencias del deporte y que los trabajos publicados en esta fuente primaria optan a una excelente visibilidad. Asimismo, en virtud de los resultados, se argumentan posibles acciones de mejora: aumentar el número de artículos por número, incrementar el porcentaje de mujeres y la internacionalidad de los miembros de los distintos Consejos de la revista, y ofrecer la posibilidad de que los investigadores que no hablen español puedan publicar sus artículos exclusivamente en inglésThe International Journal of Medicine and Science of Physical Activity and Sport is a Spanish magazine indexed in the two most important databases globally, with which impact indexes are calculated: Web of Science and Scopus. The present study analyses bibliometrically this magazine from its appearance until 2011. A total of 287 articles were published, with an average of 2.8 authorships per article. We can conclude that it is one of the best magazines in Spanish dealing with sports sciences and that the articles published in this primary source enjoy excellent visibility. Likewise, in light of the results, possible improvement actions are suggested: increasing the amount of articles per number, increasing the percentage of women and the internationality of the members of the different Boards of the magazine, and offering the possibility that researchers that do not speak Spanish may publish their articles in English only

Review of recent advances in the application of the wavelet transform to diagnose cracked rotors

Wavelet transform (WT) has been used in the diagnosis of cracked rotors since the 1990s. At present, WT is one of the most commonly used tools to treat signals in several fields. Understandably, this has been an area of extensive scientific research, which is why this paper aims to summarize briefly the major advances in the field since 2008. The present review considers advances in the use and application of WT, the selection of the parameters used, and the key achievements in using WT for crack diagnosis.The authors would like to thank the Spanish government for financing through the CDTI project RANKINE21 IDI-20101560

Crack detection in rotating shafts based on 3x energy: analytical and experimental analyses

Maintenance is essential to prevent catastrophic failures in rotating machinery. A crack can cause a failure with costly processes of reparation, especially in a rotating shaft. In this study, the wavelet transform theory was applied to vibration signals to detect cracks in a rotating shaft. Data were obtained from an analytical Jeffcott rotor model with a breathing function to simulate cracks. Large changes in energy when a crack appears were discovered at 1 ×, 2 × and 3 ×. Thereafter, vibration signals were obtained from a rotating machine at different steady-state rotational speeds using an accelerometer mounted on the bearing housing. Nine defect conditions were induced in the shaft (with depths from 4% to 50% of the shaft diameter). By matching the theoretical results with the experimental data, it was found that only the 3 × component of the rotational speed is a clear indicator of the presence of a crack in this case. The energy level at this harmonic can be used for the inverse process of crack detection. Moreover, “probability of detection” curves were calculated. They showed very good results.The authors would like to thank the Spanish Government for financing through the CDTI project RANKINE21 IDI-20101560.Publicad

Automatic condition monitoring system for crack detection in rotating machinery

Maintenance is essential to prevent catastrophic failures in rotating machinery. A crack can cause a failure with costly processes of reparation, especially in a rotating shaft. In this study, the Wavelet Packets transform energy combined with Artificial Neural Networks with Radial Basis Function architecture (RBF-ANN) are applied to vibration signals to detect cracks in a rotating shaft. Data were obtained from a rig where the shaft rotates under its own weight, at steady state at different crack conditions. Nine defect conditions were induced in the shaft (with depths from 4% to 50% of the shaft diameter). The parameters for Wavelet Packets transform and RBF-ANN are selected to optimize its success rates results. Moreover, ‘Probability of Detection’ curves were calculated showing probabilities of detection close to 100% of the cases tested from the smallest crack size with a 1.77% of false alarms.The authors would like to thank the Spanish Government for financing through the CDTI project RANKINE21 IDI-20101560

Influence of tragacanth gum in egg white based bioplastics: Thermomechanical and water uptake properties

This study aims to extend the range of applications of tragacanth gum by studying its incorporation into bioplastics formulation, exploring the influence that different gum contents (0–20 wt.%) exert over the thermomechanical and water uptake properties of bioplastics based on egg white albumen protein (EW). The effect of plasticizer nature was also evaluated through the modification of the water/glycerol ratio within the plasticizer fraction (fixed at 40 wt.%). The addition of tragacanth gum generally yielded an enhancement of the water uptake capacity, being doubled at the highest content. Conversely, presence of tragacanth gum resulted in a considerable decrease in the bioplastic mechanical properties: both tensile strength and maximum elongation were reduced up to 75% approximately when compared to the gumfree system. Ageing of selected samples was also studied, revealing an important effect of storage time when tragacanth gum is present, possibly due to its hydrophilic character.Ministerio de Economía y Competitividad (MAT2011-29275-C02-01

Application of Computational-Experimental Methods for Designing Optimized Semitrailer Axle Supports

Computational and experimental methods were applied to the design and optimization of a semitrailer axle support subjected to fatigue loads. Numerical results based on the finite element method (FEM) were correlated with extensometric tests to assess the accuracy of the computational method. This paper is focused on the “minimum radius manoeuvre.” This situation represents the highly critical load case occurring in a semitrailer operation where the tractor vehicle pulls the semitrailer’s kingpin at approximately 90° with respect to its longitudinal axis, and high stress and strain phenomena take place in the axle supports’ structure. Loads and boundary conditions that correspond to this load case were first adjusted by means of experimental tests and could be later applied to each semitrailer axle support in the numerical model. In this analysis, the stress-strain elastic-plastic curves of the base material, the welding, and the HAZ have been incorporated to the numerical models. Fatigue ¿-¿ curves combined with the maximum Von Mises equivalent stresses obtained in the computational analysis provided a maximum number of cycles that the semitrailer axle support could reach in case of the minimum radius manoeuvre being applied to the vehicle in a repeated manner. The initial design could then be optimized to improve its fatigue life

EMD-Based Methodology for the Identification of a High-Speed Train Running in a Gear Operating State

An efficient maintenance is a key consideration in systems of railway transport, especially in high-speed trains, in order to avoid accidents with catastrophic consequences. In this sense, having a method that allows for the early detection of defects in critical elements, such as the bogie mechanical components, is a crucial for increasing the availability of rolling stock and reducing maintenance costs. The main contribution of this work is the proposal of a methodology that, based on classical signal processing techniques, provides a set of parameters for the fast identification of the operating state of a critical mechanical system. With this methodology, the vibratory behaviour of a very complex mechanical system is characterised, through variable inputs, which will allow for the detection of possible changes in the mechanical elements. This methodology is applied to a real high-speed train in commercial service, with the aim of studying the vibratory behaviour of the train (specifically, the bogie) before and after a maintenance operation. The results obtained with this methodology demonstrated the usefulness of the new procedure and allowed for the disclosure of reductions between 15% and 45% in the spectral power of selected Intrinsic Mode Functions (IMFs) after the maintenance operation.The research work described in this paper was supported by the Spanish Government through the MAQ-STATUS DPI2015-69325-C2-1-R project. Authors would also thank the support provided by the participating companies (Renfe, Alstom Spain, SKF Spain, and Dano-Rail-Danobatgroup Railway) in this project

Condition monitoring of critical mechanical elements through Graphical Representation of State Configurations and Chromogram of Bands of Frequency

Fault detection is a crucial aspect to avoid catastrophic failures on mechanical systems, as well as to save money for companies. Currently, a number of non-destructing tests, signal processing analysis and artificial intelligence techniques are used for processing larger and larger amounts of maintenance data in all industry fields, either independently or combined. This manuscript presents a novel methodology for the condition monitoring of machinery, based on vibration analysis. The methodology is supported on two novel signal processing techniques: Graphical Representation of State Configurations (GRSC) and Chromogram of Bands of Frequency (CBF). These two new techniques apply basic concepts of the machine deterioration theory to the frequency spectrum. In order to prove the successful of the work presented, the methodology is tested against two real examples: vibration signals from the Case Western Reserve University (CWRU) Bearing Data Centre, and vibration signals from a high-speed train in normal operation. The results show that these new techniques can process large amounts of data without using artificial intelligence, identify adequately the operating condition of the tested systems and give precise information about that operating system by means of simple graphs and colours.The work is supported by the Spanish Government through the MAQ-STATUS DPI2015-69325-C2-1-r project